Phonographic apparatus



Sept. 14, 1937.

F. E.'RUN'GE 2,092,892 PHONOGRAPHIC APPARATUS Filed Dec. 31, 1935Patented Sept. 14, 1937 UNITED STATES 2,092,892 PHONOGRAPHIO APPARATUSFrank E. Runge, Oakiyn, N. J assignor to Radio Corporation of America,

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a corporation of Dela- Application December 31, 1935, Serial No. 56,884

'11 Claims.

This invention relates to phonographic apparatus, and more particularlyto sound recording and reproducing apparatus of the type employing aphotographic disc whereon the sound is recorded in the form of anuninterrupted spiral, the present invention being an improvement uponthat disclosed and claimed in the co-pending application of Ellsworth D.Cook, Serial No. 704,605, assigned to the Radio Corporation of America.

In said co-pending application, there is disclosed a phonographemploying a record on which the sound is recorded in the form of anArchimedean spiral track, a stationary light source and associatedoptical system focusing a fine line of light radially across the recordso as to include all the spirals or sound track turns across one radius.On the other side of the record, a stationary photoelectric cell isdisposed, the active element of the cell having a' length equal to thelength of the radial light line and being in alignment therewith. Inorder to mask off all the light except that desired at the reproducingpoint, an opaque mask provided with an Archimedean, transparent spiralis placed adjacent the record so that the spiral record track and thespiral in the mask will have the same geometrical center. Since the rateof radius change of an Archimedean spiral is constant throughout itslength, it is possible, by choosing a scanning spiral of proper pitchand rotating it at a suitable speed relative to that of the record, tocause the two spirals to intersect each other along the aforesaid radiallight line, whereby only that portion of record spiral which is inalignment with both the scanning spiral and the light line at anyinstant will serve to affect the light passing to the photoelectric cellat that instant.

While a-system using a scanning mask of the foregoing type workssatisfactorily, it leaves open several sources of noise generation whichmight be serious enough, at times, to interfere with the properreproduction of sound. In the first place, since successive transverseportions of the entire length of the scanning spiral are made 'use ofduring the reproduction of a record and since, even despite the exerciseof great care in forming the scanning spiral, it is hardly possible toform a spiral having absolutely uniform width throughout its length, itis obvious that variations inits width along its length will result in amodulation of the reproducing beam not intended by the record.Similarly, in the case of a. scanning spiral formed on a photographicdisc or plate, if dustvor other foreign matter should accumulate 5 onthe transparent scanning spiral, the reproducing beam will beunintentionally modulated. Now, if this modulation takes place at afrequency within the audible range, it is obvious that unrecorded andundesirable noises due entirely to variations in width of or foreignmatter upon the scanning spiral will result.

According to another well known form of phonograph of the photographicdisc type, the scanning element is in the form of a disc or plate havinga small aperture therein and forming a part of an optical housing whichis moved radially across the record. Such a system is shown, forexample, in the patent to Dirzuweit, No. 865,574. With a system of thissort, however, relatively complicated machinery is necessary to actuatenot only the scanning element, but also the optical system, the lightsource, and the .housing and supporting structure therefor.

Moreover, a system of this sort needs continual resetting and adjustmentbefore it can be used again once a record has been played.

of sound may be obtained without introduction of extraneous sounds alongwith the intentionally recorded sound.

Another object of my invention is to provide an improved record forphotophonographlc apparatus of the type aforesaid, which record willitself serve to direct the sound track scanning means thereacross in amanner suitable. for scanning the sound track.

It is also an object of my invention to provide an improved record asaforesaid in which the possibility of cross-talk, or the simultaneousreproduction of two adjacent lines of the spiral sound track, isentirely eliminated.

A further object of-my invention is to provide an improved record of thetype specified which will effectively set into operation, at thecompletion of playing thereof, suitable mechanism to cause repetition ofthe record.

Still another object of my invention is to provide an improved opticalsound record which will permit simplification of the sound trackscanning means.

A further object of my invention is to provide an improved optical soundrecord wherein accurate focussing' of the recording or reproducing lightbeam, as the case may be, will be assured.

- It is also an object of my in'vention to provide apparatus and recordsof the type specified which will be simple in construction and highlyefficient in use. y

In accordance with my invention, I form on one surface of a transparentdisc a spiral photographic record of sound or other desired pulsations,and on the opposite side thereof, I form 9,

the record may be repeated. If desired, the sec ond side of the disc(that is, the side on'which the guide groove'is provided) may beprovided with a spiral, transversely-curved ridge or lenticulationadapted to act as a lens for properly focussing the light beam onto theemulsion side of the disc.

The novel features that I' consider characteristic of my invention areset forth with particularity in the appended claims. The inventionitself, however, both as to its organization and method of operation,together with additional objects and advantages thereof, will best beunderstood from the following description, when read in connection withthe accompanying drawing, in which Figure 1-is a perspective view of areproducing system employing one form of record in accordance with myinvention,

Figure 2 is a sectional view taken substantially on the line 2-2 ofFigure 1,

Figure 3 is a fragmentary sectional view showing a modified form ofrecord formed in accordance with my invention, and

Figure 4 is a view, partly in elevation and partly in section, showing amodified form' of optical housing which may be employed in connectionwith this invention.

Referring more specifically to the drawing, wherein similar referencecharacters designate corresponding parts throughout, I have shown amotor I the spindle 3 of which carries and drives a record disc 5 formedof transparent material, such as glass, and the lower surface of whichmay be provided with a photographic emulsion. In the specificillustration, the record disc is one which has been exposed to lightfluctuations representative of sounds, for example, and subsequentlydeveloped to form an opaque spiral sound track I thereon. If desired, aplurality of rollers 6, either idling or driven at the proper speed, mayalso be provided to further support the disc 5 and the mechanismpresently to be described,

while driving connection between the record disc 5 and the spindle 3 maybe obtained in any suitable manner, as by tightly clamping the disc 5between a collar 8 fixed to the spindle 3 and a member ,ID threaded onthe upper end of the spindle.

The upper surface of the disc 5 is provided with a spiral groove 9 whichis longer than and extends beyond the extremities of the sound track 1and serves to guide a sound track scanning member H inwardly over therecord as it is rotated, whereby to scan the sound track I. The guidegroove 9 has a few turns 9a of fine pitch adjacent the periphery of therecord disc, thereafter passes between the turns of the sound track Iand has the same pitch as the sound track of Figure 1.

throughout the length thereof, and finally terminates in a closed,circular groove l3, preferably eccentric to the disc 5. A stylus or pin15 on the scanning member ll coacts with the groove 9 to move thescanning member H inwardly, the groove turns 9a insuring properengagement of the stylus l5 with the groove 9 in advance of the soundtrack 1, and the terminal groove l0 being effective to initiate, in wellknown manner, through an arm I! which carries the "scanning member ll,suitable mechanism for either automatically stopping rotation of thedisc 5 at the end of reproduction of the record, or for resetting thestylus [5 in the groove turns 9a to repeat the record.

Light from a suitable source within the casing of the'scanning member iiis focussed at I9 on the track by a suitable optical system also withinthe scanning member casing and having its optical axis coincidingsubstantially with the center line of the track 1. After passing throughthe disc 5 and being modulated by the sound track I, the light strikes astationary photoelectric cell 2| under the disc 5 which is connected toa suitable amplifier (not shown), the active element of the cell 2|extending substantially radially across the disc 5, or in line with thepath of movement of the'scanning member ll over the record.

In Figure 3, I have shown a modified form of record wherein a spiralridge or lenticulation 23 adapted to serve as a lens is formed on thesurface of the disc 5 opposite the emulsion surface. The lenticular lensspiral 23 is superposed over and has the same pitch as the sound trackspiral l and is provided with a suitable curvature to either focus thelight on the track I by itself or to cooperate with the optical systemin the scanning member casing for this purpose. Preferably, thelongitudinal edges 25 of adjacent turns of the ridge,23 substantiallytouch each other whereby to provide a spiral stylus guiding groove 21therebetween corresponding to the groove 9 From the foregoingdescription, it will be apparent that I have provided a novel record andimproved photophonographic apparatus that has a number of advantagesover that shown in the above-identified co-pending application ofEllsworth D. Cook, the chief of which is that the record disc does nothave to be positioned accurately with respect to the scanning member.The record disc may commence rotation from any position of \rest and thesound track accurately reproduced right from the beginning by placingthe guiding stylus l5 in any one of the groove turns So. Many otheradvantages will, no doubt, also be apparent. Also, many changes in andmodifications of the invention herein described will undoubtedly suggestthemselves to those skilled in the art. For example, the guide groove 9of Figure 1 may be formed on the same surface as the sound track I, orthe groove 9 and the lenticular lens 23 of Figure 3 may be formed on thelower surface of the record and the sound track on the upper surface,with a corresponding transposition of the scanning member H and thephotoelectric cell 2i. However, I prefer the arrangement shown in theaccompanying drawing for the reason that this prevents accumulation ofdust and other foreign matter on the emulsion surface of the disc 5, andthe further reason that the emulsion surface is protected against injuryby the stylus [5, as by accidental placement thereon. Also, if desired,a photoelectric cell which is movable with the scanning member ll may beprovided instead of being fixed, somewhat after the manner of that shownin the patent to Prescott and Kolster, No. 1,766,046. Furthermore, thestylus l5 may be made vertically adjustable in the conventional mannerwithin a socket 29 in the housing of the scanning member II and locked'in adjusted position by means-of a set screw 3|, as shown in Figure'4,for permiting focussing of the optical system of the scanning member I].I desire, therefore, that my invention shall not be limited exceptinsofar as is necessitated by the prior art and by the spirit of theappended claims.

I claim as my invention:

1. In photophonographic apparatus, the combination of a rotatable recordhaving a spiral sound track on one surface thereof and a spiral ridge onthe opposite surface thereof, said ridge having the same pitch as saidsound track and being superposed thereover, the longitudinal edges ofadjacent turns of said ridge subtantially touching each other whereby toprovide a spiral guide groove between said ridge turns, a recordscanning member associated with said record, and means associated withsaid scanning member and adapted to cooperate with said guide groove forcausing said scanning member to be fed across said record as the recordis rotated.

2. In phonophotographic apparatus, the combination of a rotatabletransparent record having an opaque sound track on one surface thereofand a spiral ridge constituting a lens on the opposite surface thereof,said ridge having the same pitch as said sound track and beingsuperposed thereover, the longitudinal edges of ad-. jacent turns ofsaid ridge substantially touching each other whereby to provide a spiralguide groove between the ridge turns, a record scanning memberassociated with said record, said scanning member and said ridge lenscooperating to focus a light beam onto said sound track, and meansassociated with said scanning member and adapted to cooperate with saidguide groove for causing said scanning member to be fed across saidrecord as the record is rotated.

3. A sound record comprising a disc, a spiral record of sound on onesurface thereof, and a spiral stylus guiding groove on the oppositesurface thereof, said spiral groove having several turns of fine pitchadjacent the periphery of the disc, thereafter continuing between theturns of said sound spiral, and finally terminating in a closed circulargroove.

4. A sound record comprising a disc, a spiral record of sound on onesurface thereof, and a spiral stylus guiding groove on the oppositesurface thereof, said spiral groove having several turns of flne pitchadjacent the periphery of the disc, thereafter continuing between theturns of said sound spiral, and finally terminating in a closed circulargroove eccentric to said disc.

5. A phonograph record comprising a transparent disc, an emulsion layeron one surface of said disc adapted to have a signal representing trackformed thereon, and a guiding groove on the opposite surface thereof forguiding an element'having cooperative relation with said track.

6. A sound record comprising a transparent disc, an opaque spiral soundtrack on one surface thereof, and spiral stylus guiding means on theopposite surface thereof, said stylus guiding means having its turnslying between the turns of said sound track.

7. A sound record comprising a transparent disc, an opaque spiral soundtrack on one surface thereof, a spiral stylus guiding groove on theopposite surface thereof, said spiral groove. extending beyond the endsof said sound track and being of the same pitch as said sound trackthroughout the length of the latter.

8. A sound record comprising a transparent disc, an opaque spiral soundtrack on one surface thereof, a spiral stylus guiding groove on theopposite surface thereof, said spiral groove extending beyond the endsof said sound track and being of the same pitch as said sound trackthroughout the length of the latter but having a plurality of turnsadjacent the periphery of the disc of finer pitch than saidsound trackand terminating in a closed circular groove adjacent the center of saiddisc.

9. A sound record comprising a transparent member having an opaque soundtrack on one surface thereof, and a lenticular portion on the oppositesurface thereof adapted to act as a lens for focusing a light beam ontosaid sound track.

10. A sound record comprising atransparent member having an opaque soundtrack on one surface thereof, and a, lenticular portion on the oppositesurface thereof in alignment with said sound track, said lenticularportion being adapted to act as a lens for focusing a light beam ontosaid sound track.

11. A sound record comprising a transparent disc having an opaque,spiral sound track on one surface thereof, and a spiral lenticulation onthe opposite surface thereof of the same pitch as and in alignment withsaid sound track, said lenticulation being adapted to serve as a lensfor focusing a. light beam onto said sound track and having thelongitudinal edges of adJacent turns thereof substantially touching eachother whereby to provide a. spiral guide groove therebetween.

FRANK E. R'UNGE.

